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Screening for Thyroid Disease
- American College of Physicians*. * This paper, written by Mark Helfand, MD, Craig C. Redfern, DO, and Harold C. Sox, MD, was developed by the Clinical Efficacy Assessment Subcommittee: George E. Thibault, MD, Chair, Anne-Marie J. Audet, MD; John R. Feussner, MD; Gottlieb C. Friesinger II, MD; Daniel L. Kent, MD; Keith I. Marton, MD; Valerie Anne Palda, MD; and Humberto J. Vidaillet Jr., MD. Approved by the Board of Regents on 6 March 1997. Requests for Reprints: Customer Service Representative, American College of Physicians-American Society of Internal Medicine, 190 North Independence Mall West, Philadelphia, PA 19106-1572.
The numbers in square brackets are cross-references to the numbered paragraphs in the accompanying background paper, “Screening for Thyroid Disease: An Update,” which is part 2 of this guideline (see pages 144-158).
Screening is “the application of a test to detect a potential disease or condition in a person who has no known signs or symptoms of that condition at the time the test is done” [1]. Screening with thyroid function tests can identify clinically inapparent subclinical thyroid dysfunction. Subclinical hypothyroidism is diagnosed when a patient has an elevated thyroid-stimulating hormone (TSH) level as determined by a sensitive TSH test and a normal thyroxine level. Subclinical hyperthyroidism is diagnosed when a patient has an undetectable TSH level and a normal thyroxine level. Screening also detects overt thyroid dysfunction, which is diagnosed when a patient has an elevated TSH level and a low thyroxine level (overt hypothyroidism) or an undetectable TSH level and an elevated thyroxine level (overt hyperthyroidism).
In 1990, the American College of Physicians published guidelines on screening for thyroid disease [2, 3]. These guidelines recommended the use of thyroid function tests to identify symptomatic but clinically unrecognized overt hypothyroidism and thyrotoxicosis in women older than 50 years of age. Since 1990, studies of screening have confirmed that even in clinic patients who receive regular care, screening can identify symptomatic overt hypothyroidism or hyperthyroidism that was not suspected in the usual course of care.
The 1990 guidelines recommended against screening for subclinical thyroid failure in the general population because evidence that such patients benefit from earlier detection and treatment was insufficient. Subclinical hypothyroidism (also called mild thyroid failure) may be associated with nonspecific symptoms, hypercholesterolemia, and progression to overt hypothyroidism. Studies performed since 1990 have added to the …
